Regarding the indication of the quantity of gasoline in a gasoline tank buried in the underground of a gasoline station, various indicating methods have been considered depending upon the shapes of the tanks.
For example, in case where the tank is in the shape of a rectangular parallelepiped, the quantity of gasoline can be readily known by sensing the liquid level of the gasoline in the tank. The same applies to a cylindrical tank of the vertical type.
In case of a cylindrical gasoline tank of the horizontal type, however, the quantity of gasoline received in the tank cannot be readily known even when the liquid level of the gasoline has been known. Only one method has been to calculate the quantity of the received gasoline with a segmental function table.